Broke sobriety, what to do?

I’m afraid to ask my family and friends about this because they might judge me or worse they might give up on me. I don’t know what I should do after breaking my year-long sobriety from alcohol. I had a mildly severe addiction to alcohol and went to a rehab program for it. It wasn’t easy but I felt better in the end. But I betrayed myself by drinking a shot of vodka in this international brides dating social event that I got invited in. I didn’t really want to drink but my old friends kept pressuring me, told me it wouldn’t harm me. Now, I’m paranoid that I might relapse after that incident. Should I contact a therapist? Do I go back to my old rehab center?

What do you do for current sobriety support?
I go to AA meetings to talk about my issues. You might get some experienced answers from others who have been through a 'slip' and what they did about it.
Total relapse does not have to be a requirement after a slip.
Stopping is easy if you are placed in a rehab, staying stopped is more of a challenge. I know for me that it gets more and more difficult to stop drinking after going back out. At this point I don't know if I would make it back. I won't place myself in dangerous situations without a backup plan. I usually carry my coin in my pocket when I go out where alcohol will be present and hold on to it for reassurance.
My family and friends already know that I don't drink, so I don't get offered a drink.
Alcoholism is chronic and progressive. It would get much harder to quit as it progresses.
Best of luck to you.